Lubricant, etc.



Marsh 9 194%, A. BEERBOWER ET AL 2,343,735

' LUBRICANT, mo

Filed Aug. 28, 1942 TRAN$ I 7'! ON 2712A NSITION TQM/27R TOWER WATER"v4.57-

WATE? OUTLET 4/0? one: ,srock INLET Patented Mar. 7, 19

, LUBRICANT, ETQ.

Alan Beerbower and Austin E. Calkins, Westileld, N. 3., assignors toStandard Oil Development Qompany, a corporation of Delaware ApplicationAugust 28,1942, Serial No. 456,49d

4 Claims.

This invention relates to a novel method and apparatus for manufacturinglubricating greases, more particularly aluminum greases.

Aluminum soap greases have been shown to be outstanding automotive,chassis and tractor roll lubricants but the processing difficultiesencountered in their manufacture have restricted their use. Whilealuminum soap greases can be readily compounded from aluminum stearateand oil at 280 to 300 F., it is subsequently necessary to cool thegreases to a transition temperature of usually about 120 to 150 F. Thegrease must then not be disturbed while it changes from stringy liquidto a solid gel, which requires from two to eight hours, or so. Attemptsto cool the grease in shipping containers result in a wide variation inconsistency, ranging from a hard grease on the outer edge of the barrelto a soft fluid oil in the center; also the consistency varies greatlywith different sized containers. Consequently aluminum soap greases haveusually been manufactured by pouring the hot liquid grease into shallowpans holding from 100-500 lbs. of grease, and allowing it to coolovernight, after which it is subsequently shoveled back into the kettle,stirred and filtered into containers. Large floor space is necessary forthis pan method of cooling, and an excessive amount of labor is requiredto handle the product. method, which for convenience might be referredto as the kettle-cfioling method, the hot grease is cooled to about 160F. in a special scraped shipment. The vertical towers transition zoneshould have a capacity of not much more than half of the capacity of thegrease cooking kettle, if two towers are used alternatively, or not muchmore than one-third constituting the the capacity, if three towers areused. These well insulated on the outside or jacketed to pro- In anotherkettle, and allowed to stand unstirred overnight,

after which it is stirred and filtered as' it leaves the kettle. Thepresent invention comprises a method for delivering the grease cooled ina semicontinuous manner and eliminates the need for a special kettle,replacing it by simple equipment. It has the advantage of being useablewith continuous grease blending equipment, whereas the kettle-coolingmethod is not. The present invention also has many advantages over thepancooling method.

Broadly the invention comprises quickly cooling the hot aluminum soapgrease in a suitable cooling zcne down to a temperature not more than afew degrees above the transition temperature of the grease, thentransferring it into a suitable transition zone, preferably consistingof one or more vertical towers, where the grease is pezmtted to remainsubstantially undisturbed until it has undergone transition from astringy or rubbery form to an unctuous gel-form, after which it is thenforced out through a filter into suitable cans or other containers forstorage or vide circulation-0f Water or other fluid heat transfer mediumin order to maintain the desired temperature approximately constantduring the transition period. These transition towers should preferablybe equipped with a floating piston to assist in forcing the grease outof the bottom of the tower by compressed air-after the transition iscompleted. Obviously towers of other dimensions may be used, such assmaller pipes 2" to 4" or so in diameter and 1' to 3 or so in length forsmall laboratory or pilot plant work, and larger pipes having an insidediameter up to 3' or 4' or so and up to 15' or 20 in length for largeplant operation. Generally, the length of the pipe should be at leasttwo, but not more than five, times the diameter. When compressed air isused to force the grease'back down out of the towers after transition,preferably dry air should be used so as to avoid condensation ofmoisture in the towers, especially if no floating pistonris used. Thepiston may also be moved by means of a hydraulic or screw jack, or othersuitable means.

The time required for the transition of the grease from the stringy orrubbery form to the desired smooth gel form, usually is betweenonequarter hour to six hours or so, depending primarily upon thecomposition of the grease.

The temperature maintained in the grease during the transition periodwill also vary largely according to the composition, for instance, be- Itween the approximate limits of F. and 180 F. and usually between thesomewhat narrower limits of 115 to 160 F. The upper range of thetransition temperature, i. e., about 40 to 160 F. is that required whenthe grease is made from an aluminum soap which is substantially allaluminum st'earate, whereas a lower temperature range of about to 140F., usually to F., is better for a grease made'with an aluminum soapconsisting of about 90% aluminum stearate and 10% aluminum naphthenate,and an even lower temperature range of 90 to 110 F'. is better if in thelatter composition the aluminum naphthenate is replaced by naphthenicacid.

In carrying out the invention the hot soap-oil solution to be subjectedto cooling and transition may be prepared in several ways, for instanceby dissolving an already prepared aluminum soap in a mineral oil, or byreacting aluminum hydroxide or other suitable aluminum compound with asolution of fatty acid in oil. Instead of, and in addition to, aluminumstearate and aluminum naphthenate, other soaps may be used, such asaluminum soaps of synthetic fatty acids made by the oxidation ofparafiin wax. In general the carboxylic acids having or preferablycarbon atoms or more are suitable. Also soaps may be made from saturatedfatty acids derived from fats or oils of animal, vegetable and fishorigin. In any case the proportion of aluminum soap in the finishedgrease should be about 540%, or in some cases between the broader limitsof 13-20% by weight.

The oil to be used as base stock in preparing greases according to thisinvention may be any mineral oil stock, such as used heretofore for suchpurposes, for instance light, medium, or heavy lubricating oil basestocks derived from any of the various crude oils, 1. e., of paramnic,naphthenic or mixed base crudes. These oil base stocks may be subjectedto any of the conventional refining treatments, such as distillation,clay treating, acid treating, aluminum chloride treating, solventextraction, de-asphalting, etc. For general use a pale or red oil ofmedium or heavy viscosity, from naphthenic or mixed base crudes ispreferred.

The grease cooking temperature, i. e., that to which the mixture of oiland aluminum soap must be heatedto effect proper solution or dispersionof the aluminum soap in the oil to make a completely homogeneouscomposition, will range from about 200 to 350 F., depending upon thenature and proportion of the aluminum soap used as well as on the typeof oil, but ordinarily the cooking temperature should be about 250 to300 F.

The cooler into which the hot soap-oil solution or dispersion is passedin order to cool it down to a temperature not more than a few degrees,such as 10 or less above the grease transition temperature, may consistof ordinary pipe coils surrounded by a suitable cooling medium, such aswater (preferably having a temperature not substantially below 100 F),so as to avoid undue hardening of the grease on the inside of thecooling coils, or which may consist of a jacketed kettle through whichcooling water of proper temperature may be circulated, but it ispreferably a helical conveyor such as the Carbondale scraped waxchiller. Such a chiller may have, for instance, a diameter of 6" and alength of 40' or so for commercial operation, or about 1" to 1%" or soin diameter with a length of about to 3' for laboratory or pilot plantoperation. In either case the pipe containing the helical or screwconveyor should be jacketed or surrounded by another pipe having warmwater circulating through it to keep the temperature fairly constant andto prevent graininess.

After the soap-oil solution or dispersion has been cooled to near thetransition temperature and then passed into the transition tower for therequired transition period and has attained the desired smooth unctuousgel or grease structure, it is then forced back out of the transitiontowers,

filtered and filled into cans, barrels or other suitable containers forshipping or storage.

The finished aluminum grease made according to this invention shouldnormally have a worked penetration within the approximate limits of300-400, preferably 320-350, according to the A. S. T. M. penetrationtest, when the grease contains 5-10% of soap, but lower if more soap isused.

The objects and advantages of the invention will be still betterunderstood from a description of the accompanying drawing and theexamples which follow.

Referring to the accompanying drawing, a hot aluminum stearate soap-oilsolution or dispersion made by conventional methods, such as thosedescribed above, and issuing from a suitable source not shown(preferably continuous), and having 'a temperature of about 280 to 300F., is fed through line I to cooler 2 from whence it issues at atemperature of about 150 to 160 F. through line 3 into one of thetransition towers 4 in which the incoming grease composition raises thefloating piston 5 and in which after filling this grease composition ispermitted to remain substantially undisturbed for the requiredtransition period until the composition has acquired the desired greasestructure, after which it is forced, by compressed air from line 5, backout of the tower 4, through line 7, through filter 8 into suitable canor barrel filling equipment, not shown. The filling pump 9 may beprovided between line i and filter 8 to assist in forcing the greasethrough the filter into the cans and barrels for shipment or storage.

Example 1 A grease was prepared with the following formula:

Heavy lube 011 (200 seconds viscosity at Medium lube oil secondsviscosity at 210 F.) 78.25 Polyisobutylene (mol. wt. about 30,000) 0.05

An aluminum grease was made with a composition identical with that usedin Example 1, except that the 8% of soap used consisted entirely ofaluminum stearate (no naphthenate being used). This composition produceda grease of very satisfactory texture with a worked pene tration of 352,the temperature in the tower Jacket being maintained at about to F.Example 3 Another batch of grease was made with the same formula as usedin Example 2, except that the aluminum stearate used was obtained from adifferent manufacturer than the one from which the aluminum stearateused in Example 2 was obtained. With a transition temperature of 150 F.,a grease of very good quality and excellent appearance was obtainedhaving :1 Worked penetration of 341.

Example 4 A grease of the following composition was pre-. pared:

This material was cooled to 95 F. and maintained at this temperature forfour hours in the tower described in Example 1. A semi-fluid lubricantsuitable for tractor or tank lubrication was produced. 1

It is not intended that this invention be limited to any of the specificexamples which have been given merely for the sake of illustration norto the specific embodiment of the invention as illustower-shapedtransition zone and letting it remain there substantially undisturbedand at a substantially constant temperature for a transition period ofabout one-quarter hour to six hours 5 until it has acquired the desiredgrease structure,

trated in the drawing, but only by the appended claims in which it isintended to claim all novelty inherent in the invention as well as othermodifications coming within the scope and spirit of the invention.

We claim:

1. The process of manufacturing an aluminum soap grease which comprisesmaking a hot grease stock comprising about -95% ofmineral lubricatingoil and about'5-10% of an aluminum soap of high molecular weightcarboxylic acid, having a temperature of 280 to 300 F., cooling it tonear its transition temperature, between the approximate limits of 90and 180 F., depending upon its composition, passing it to a vertical andthen filtering the grease.

2. Process according to claim '1 in which the aluminum soap used inmaking the grease stock comprises about 80-95% "or aluminum stearate andabout 20-5% of aluminum naphthenate and the transition temperature isheld at to F.

3. Process according to claim 1, in which the aluminum soap usedcomprises about 80-95% of aluminum stearate and about 20-5% ofnaphthenic acid, and the transition temperature is held at about 100 toF.

4. A semi-continuous process for manufacturing aluminum soap greasewhich comprises continuously making a hot grease stock comprising about90-95% of oil and about 105% of aluminum soap, having a temperature of280 to 300 F., continuously cooling said grease stock to near itstransition temperature, continuously passing the cooled grease stockinto one of a plurality of vertical transition towers containing afloating piston to cover the upper surface of the grease in said tower,permitting said grease stock to remain undisturbed in said transitiontower for a sufficient period of about one-quarter hour to six hours toacquire the desired grease structure, continuously forcing the finishedgrease out 01' one of a plurality of such transition towers through afilter and into suitable containers for storage and/or shipment.

ALAN BEERBOWER. AUSTIN E. CALKINS.

